What the Rules Require
Gas pipelines under 49 CFR 192.465 and hazardous liquid lines under 49 CFR 195.575 require cathodic protection facilities to be tested to confirm they work. Rectifiers and other power sources get checked at least 6 times a year, not more than 2.5 months apart. Test stations and bonds are read annually. If the criteria are not met, the operator acts and records the fix.
What a Reading Tells You
A pipe-to-soil potential reading near or beyond the protection criteria indicates the pipe is polarized and corrosion is being suppressed. A reading that drifts positive means protection is lost: a dead rectifier, a broken wire, a coating failure. The point of the schedule is to catch the loss before the leak.
The Record That Matters
DOT records must show the date, the reading, and who took it, for each test location. Operators must also monitor for interference from foreign structures and document corrective action. The paper trail is the program. Missed readings and missing records are the violations that turn up in inspections.
The record that closes the loop
Cathodic Protection Testing rests on the same field data as the rest of the operation: tickets, timesheets, approvals, and inspections. The same discipline shows up in Pipeline integrity for gathering lines and Operator qualification for pipeline work and Saltwater disposal well operations. If those records live in notebooks, email, and memory, start with an operations audit.